/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.buffer;

import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;

import io.netty.util.internal.PlatformDependent;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.nio.channels.GatheringByteChannel;
import java.nio.channels.ScatteringByteChannel;

/**
 * A NIO {@link ByteBuffer} based buffer. It is recommended to use {@link
 * UnpooledByteBufAllocator#directBuffer(int, int)}, {@link Unpooled#directBuffer(int)} and {@link
 * Unpooled#wrappedBuffer(ByteBuffer)} instead of calling the constructor explicitly.
 */
public class UnpooledDirectByteBuf extends AbstractReferenceCountedByteBuf {

  private final ByteBufAllocator alloc;

  private ByteBuffer buffer;
  private ByteBuffer tmpNioBuf;
  private int capacity;
  private boolean doNotFree;

  /**
   * Creates a new direct buffer.
   *
   * @param initialCapacity the initial capacity of the underlying direct buffer
   * @param maxCapacity the maximum capacity of the underlying direct buffer
   */
  public UnpooledDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity) {
    super(maxCapacity);
    if (alloc == null) {
      throw new NullPointerException("alloc");
    }
    checkPositiveOrZero(initialCapacity, "initialCapacity");
    checkPositiveOrZero(maxCapacity, "maxCapacity");
    if (initialCapacity > maxCapacity) {
      throw new IllegalArgumentException(String.format(
          "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
    }

    this.alloc = alloc;
    setByteBuffer(allocateDirect(initialCapacity));
  }

  /**
   * Creates a new direct buffer by wrapping the specified initial buffer.
   *
   * @param maxCapacity the maximum capacity of the underlying direct buffer
   */
  protected UnpooledDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer,
      int maxCapacity) {
    super(maxCapacity);
    if (alloc == null) {
      throw new NullPointerException("alloc");
    }
    if (initialBuffer == null) {
      throw new NullPointerException("initialBuffer");
    }
    if (!initialBuffer.isDirect()) {
      throw new IllegalArgumentException("initialBuffer is not a direct buffer.");
    }
    if (initialBuffer.isReadOnly()) {
      throw new IllegalArgumentException("initialBuffer is a read-only buffer.");
    }

    int initialCapacity = initialBuffer.remaining();
    if (initialCapacity > maxCapacity) {
      throw new IllegalArgumentException(String.format(
          "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
    }

    this.alloc = alloc;
    doNotFree = true;
    setByteBuffer(initialBuffer.slice().order(ByteOrder.BIG_ENDIAN));
    writerIndex(initialCapacity);
  }

  /**
   * Allocate a new direct {@link ByteBuffer} with the given initialCapacity.
   */
  protected ByteBuffer allocateDirect(int initialCapacity) {
    return ByteBuffer.allocateDirect(initialCapacity);
  }

  /**
   * Free a direct {@link ByteBuffer}
   */
  protected void freeDirect(ByteBuffer buffer) {
    PlatformDependent.freeDirectBuffer(buffer);
  }

  private void setByteBuffer(ByteBuffer buffer) {
    ByteBuffer oldBuffer = this.buffer;
    if (oldBuffer != null) {
      if (doNotFree) {
        doNotFree = false;
      } else {
        freeDirect(oldBuffer);
      }
    }

    this.buffer = buffer;
    tmpNioBuf = null;
    capacity = buffer.remaining();
  }

  @Override
  public boolean isDirect() {
    return true;
  }

  @Override
  public int capacity() {
    return capacity;
  }

  @Override
  public ByteBuf capacity(int newCapacity) {
    checkNewCapacity(newCapacity);

    int readerIndex = readerIndex();
    int writerIndex = writerIndex();

    int oldCapacity = capacity;
    if (newCapacity > oldCapacity) {
      ByteBuffer oldBuffer = buffer;
      ByteBuffer newBuffer = allocateDirect(newCapacity);
      oldBuffer.position(0).limit(oldBuffer.capacity());
      newBuffer.position(0).limit(oldBuffer.capacity());
      newBuffer.put(oldBuffer);
      newBuffer.clear();
      setByteBuffer(newBuffer);
    } else if (newCapacity < oldCapacity) {
      ByteBuffer oldBuffer = buffer;
      ByteBuffer newBuffer = allocateDirect(newCapacity);
      if (readerIndex < newCapacity) {
        if (writerIndex > newCapacity) {
          writerIndex(writerIndex = newCapacity);
        }
        oldBuffer.position(readerIndex).limit(writerIndex);
        newBuffer.position(readerIndex).limit(writerIndex);
        newBuffer.put(oldBuffer);
        newBuffer.clear();
      } else {
        setIndex(newCapacity, newCapacity);
      }
      setByteBuffer(newBuffer);
    }
    return this;
  }

  @Override
  public ByteBufAllocator alloc() {
    return alloc;
  }

  @Override
  public ByteOrder order() {
    return ByteOrder.BIG_ENDIAN;
  }

  @Override
  public boolean hasArray() {
    return false;
  }

  @Override
  public byte[] array() {
    throw new UnsupportedOperationException("direct buffer");
  }

  @Override
  public int arrayOffset() {
    throw new UnsupportedOperationException("direct buffer");
  }

  @Override
  public boolean hasMemoryAddress() {
    return false;
  }

  @Override
  public long memoryAddress() {
    throw new UnsupportedOperationException();
  }

  @Override
  public byte getByte(int index) {
    ensureAccessible();
    return _getByte(index);
  }

  @Override
  protected byte _getByte(int index) {
    return buffer.get(index);
  }

  @Override
  public short getShort(int index) {
    ensureAccessible();
    return _getShort(index);
  }

  @Override
  protected short _getShort(int index) {
    return buffer.getShort(index);
  }

  @Override
  protected short _getShortLE(int index) {
    return ByteBufUtil.swapShort(buffer.getShort(index));
  }

  @Override
  public int getUnsignedMedium(int index) {
    ensureAccessible();
    return _getUnsignedMedium(index);
  }

  @Override
  protected int _getUnsignedMedium(int index) {
    return (getByte(index) & 0xff) << 16 |
        (getByte(index + 1) & 0xff) << 8 |
        getByte(index + 2) & 0xff;
  }

  @Override
  protected int _getUnsignedMediumLE(int index) {
    return getByte(index) & 0xff |
        (getByte(index + 1) & 0xff) << 8 |
        (getByte(index + 2) & 0xff) << 16;
  }

  @Override
  public int getInt(int index) {
    ensureAccessible();
    return _getInt(index);
  }

  @Override
  protected int _getInt(int index) {
    return buffer.getInt(index);
  }

  @Override
  protected int _getIntLE(int index) {
    return ByteBufUtil.swapInt(buffer.getInt(index));
  }

  @Override
  public long getLong(int index) {
    ensureAccessible();
    return _getLong(index);
  }

  @Override
  protected long _getLong(int index) {
    return buffer.getLong(index);
  }

  @Override
  protected long _getLongLE(int index) {
    return ByteBufUtil.swapLong(buffer.getLong(index));
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
    checkDstIndex(index, length, dstIndex, dst.capacity());
    if (dst.hasArray()) {
      getBytes(index, dst.array(), dst.arrayOffset() + dstIndex, length);
    } else if (dst.nioBufferCount() > 0) {
      for (ByteBuffer bb : dst.nioBuffers(dstIndex, length)) {
        int bbLen = bb.remaining();
        getBytes(index, bb);
        index += bbLen;
      }
    } else {
      dst.setBytes(dstIndex, this, index, length);
    }
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
    getBytes(index, dst, dstIndex, length, false);
    return this;
  }

  private void getBytes(int index, byte[] dst, int dstIndex, int length, boolean internal) {
    checkDstIndex(index, length, dstIndex, dst.length);

    ByteBuffer tmpBuf;
    if (internal) {
      tmpBuf = internalNioBuffer();
    } else {
      tmpBuf = buffer.duplicate();
    }
    tmpBuf.clear().position(index).limit(index + length);
    tmpBuf.get(dst, dstIndex, length);
  }

  @Override
  public ByteBuf readBytes(byte[] dst, int dstIndex, int length) {
    checkReadableBytes(length);
    getBytes(readerIndex, dst, dstIndex, length, true);
    readerIndex += length;
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuffer dst) {
    getBytes(index, dst, false);
    return this;
  }

  private void getBytes(int index, ByteBuffer dst, boolean internal) {
    checkIndex(index, dst.remaining());

    ByteBuffer tmpBuf;
    if (internal) {
      tmpBuf = internalNioBuffer();
    } else {
      tmpBuf = buffer.duplicate();
    }
    tmpBuf.clear().position(index).limit(index + dst.remaining());
    dst.put(tmpBuf);
  }

  @Override
  public ByteBuf readBytes(ByteBuffer dst) {
    int length = dst.remaining();
    checkReadableBytes(length);
    getBytes(readerIndex, dst, true);
    readerIndex += length;
    return this;
  }

  @Override
  public ByteBuf setByte(int index, int value) {
    ensureAccessible();
    _setByte(index, value);
    return this;
  }

  @Override
  protected void _setByte(int index, int value) {
    buffer.put(index, (byte) value);
  }

  @Override
  public ByteBuf setShort(int index, int value) {
    ensureAccessible();
    _setShort(index, value);
    return this;
  }

  @Override
  protected void _setShort(int index, int value) {
    buffer.putShort(index, (short) value);
  }

  @Override
  protected void _setShortLE(int index, int value) {
    buffer.putShort(index, ByteBufUtil.swapShort((short) value));
  }

  @Override
  public ByteBuf setMedium(int index, int value) {
    ensureAccessible();
    _setMedium(index, value);
    return this;
  }

  @Override
  protected void _setMedium(int index, int value) {
    setByte(index, (byte) (value >>> 16));
    setByte(index + 1, (byte) (value >>> 8));
    setByte(index + 2, (byte) value);
  }

  @Override
  protected void _setMediumLE(int index, int value) {
    setByte(index, (byte) value);
    setByte(index + 1, (byte) (value >>> 8));
    setByte(index + 2, (byte) (value >>> 16));
  }

  @Override
  public ByteBuf setInt(int index, int value) {
    ensureAccessible();
    _setInt(index, value);
    return this;
  }

  @Override
  protected void _setInt(int index, int value) {
    buffer.putInt(index, value);
  }

  @Override
  protected void _setIntLE(int index, int value) {
    buffer.putInt(index, ByteBufUtil.swapInt(value));
  }

  @Override
  public ByteBuf setLong(int index, long value) {
    ensureAccessible();
    _setLong(index, value);
    return this;
  }

  @Override
  protected void _setLong(int index, long value) {
    buffer.putLong(index, value);
  }

  @Override
  protected void _setLongLE(int index, long value) {
    buffer.putLong(index, ByteBufUtil.swapLong(value));
  }

  @Override
  public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
    checkSrcIndex(index, length, srcIndex, src.capacity());
    if (src.nioBufferCount() > 0) {
      for (ByteBuffer bb : src.nioBuffers(srcIndex, length)) {
        int bbLen = bb.remaining();
        setBytes(index, bb);
        index += bbLen;
      }
    } else {
      src.getBytes(srcIndex, this, index, length);
    }
    return this;
  }

  @Override
  public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
    checkSrcIndex(index, length, srcIndex, src.length);
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    tmpBuf.put(src, srcIndex, length);
    return this;
  }

  @Override
  public ByteBuf setBytes(int index, ByteBuffer src) {
    ensureAccessible();
    ByteBuffer tmpBuf = internalNioBuffer();
    if (src == tmpBuf) {
      src = src.duplicate();
    }

    tmpBuf.clear().position(index).limit(index + src.remaining());
    tmpBuf.put(src);
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
    getBytes(index, out, length, false);
    return this;
  }

  private void getBytes(int index, OutputStream out, int length, boolean internal)
      throws IOException {
    ensureAccessible();
    if (length == 0) {
      return;
    }
    ByteBufUtil
        .readBytes(alloc(), internal ? internalNioBuffer() : buffer.duplicate(), index, length,
            out);
  }

  @Override
  public ByteBuf readBytes(OutputStream out, int length) throws IOException {
    checkReadableBytes(length);
    getBytes(readerIndex, out, length, true);
    readerIndex += length;
    return this;
  }

  @Override
  public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
    return getBytes(index, out, length, false);
  }

  private int getBytes(int index, GatheringByteChannel out, int length, boolean internal)
      throws IOException {
    ensureAccessible();
    if (length == 0) {
      return 0;
    }

    ByteBuffer tmpBuf;
    if (internal) {
      tmpBuf = internalNioBuffer();
    } else {
      tmpBuf = buffer.duplicate();
    }
    tmpBuf.clear().position(index).limit(index + length);
    return out.write(tmpBuf);
  }

  @Override
  public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
    return getBytes(index, out, position, length, false);
  }

  private int getBytes(int index, FileChannel out, long position, int length, boolean internal)
      throws IOException {
    ensureAccessible();
    if (length == 0) {
      return 0;
    }

    ByteBuffer tmpBuf = internal ? internalNioBuffer() : buffer.duplicate();
    tmpBuf.clear().position(index).limit(index + length);
    return out.write(tmpBuf, position);
  }

  @Override
  public int readBytes(GatheringByteChannel out, int length) throws IOException {
    checkReadableBytes(length);
    int readBytes = getBytes(readerIndex, out, length, true);
    readerIndex += readBytes;
    return readBytes;
  }

  @Override
  public int readBytes(FileChannel out, long position, int length) throws IOException {
    checkReadableBytes(length);
    int readBytes = getBytes(readerIndex, out, position, length, true);
    readerIndex += readBytes;
    return readBytes;
  }

  @Override
  public int setBytes(int index, InputStream in, int length) throws IOException {
    ensureAccessible();
    if (buffer.hasArray()) {
      return in.read(buffer.array(), buffer.arrayOffset() + index, length);
    } else {
      byte[] tmp = ByteBufUtil.threadLocalTempArray(length);
      int readBytes = in.read(tmp, 0, length);
      if (readBytes <= 0) {
        return readBytes;
      }
      ByteBuffer tmpBuf = internalNioBuffer();
      tmpBuf.clear().position(index);
      tmpBuf.put(tmp, 0, readBytes);
      return readBytes;
    }
  }

  @Override
  public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
    ensureAccessible();
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    try {
      return in.read(tmpNioBuf);
    } catch (ClosedChannelException ignored) {
      return -1;
    }
  }

  @Override
  public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
    ensureAccessible();
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    try {
      return in.read(tmpNioBuf, position);
    } catch (ClosedChannelException ignored) {
      return -1;
    }
  }

  @Override
  public int nioBufferCount() {
    return 1;
  }

  @Override
  public ByteBuffer[] nioBuffers(int index, int length) {
    return new ByteBuffer[]{nioBuffer(index, length)};
  }

  @Override
  public ByteBuf copy(int index, int length) {
    ensureAccessible();
    ByteBuffer src;
    try {
      src = (ByteBuffer) buffer.duplicate().clear().position(index).limit(index + length);
    } catch (IllegalArgumentException ignored) {
      throw new IndexOutOfBoundsException("Too many bytes to read - Need " + (index + length));
    }

    return alloc().directBuffer(length, maxCapacity()).writeBytes(src);
  }

  @Override
  public ByteBuffer internalNioBuffer(int index, int length) {
    checkIndex(index, length);
    return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
  }

  private ByteBuffer internalNioBuffer() {
    ByteBuffer tmpNioBuf = this.tmpNioBuf;
    if (tmpNioBuf == null) {
      this.tmpNioBuf = tmpNioBuf = buffer.duplicate();
    }
    return tmpNioBuf;
  }

  @Override
  public ByteBuffer nioBuffer(int index, int length) {
    checkIndex(index, length);
    return ((ByteBuffer) buffer.duplicate().position(index).limit(index + length)).slice();
  }

  @Override
  protected void deallocate() {
    ByteBuffer buffer = this.buffer;
    if (buffer == null) {
      return;
    }

    this.buffer = null;

    if (!doNotFree) {
      freeDirect(buffer);
    }
  }

  @Override
  public ByteBuf unwrap() {
    return null;
  }
}
